Nowadays, a diagnostic ultrasound system is widely used to inspect an internal state of a human body. The diagnostic ultrasound system may obtain an image of a single layer or a blood flow of a soft tissue without using an invasive needle. This is typically done through the process of radiating an ultrasound signal to a desired portion in the human body from a body surface of a target object to be diagnosed, receiving the reflected ultrasound signal, and processing the received ultrasound signal (the ultrasound echo signal.) Compared to other medical imaging systems (e.g., X-ray diagnostic system, X-ray Computerized Tomography (CT) scanner, Magnetic Resonance Imaging (MR) system, nuclear medicine diagnostic system, etc.), the ultrasound diagnostic system is relatively small in size and inexpensive, capable of displaying images in real-time, highly safe from exposure to X-ray radiation etc. Due to such advantages, the ultrasound diagnostic system is extensively employed to diagnose the heart, abdomen and urinary organs, especially in the fields of obstetrics and gynecology, etc.
In order to obtain precise information on a body structure and an organ to be inspected, it is necessary to quantitize an image obtained from the ultrasound diagnostic system. Conventionally, the body structure is passively quantitized based on a static image or measured information from the static image. For example, in order to measure a growth condition of an unborn child during pregnancy or on the expected date of delivery, the static image of the unborn child should be obtained during a lower activity period of the unborn child in his/her mother's body. Further, a contour or length of the unborn child should be measured from the obtained static image over a few times.
It is, however, difficult to obtain a static image of a continuously pumping organ such as the heart since the pumping of the heart leads to a constriction and an expansion of the organ and also causes a contour of the heart to vary continuously. In this regard, in order to completely evaluate a feature of the heart's function, a number of static images (e.g., more than 30 to 150 images) should be obtained during one cycle of heart pumping to detect a boundary of the heart by measuring necessary numerical values from the static images. In this case, the numerical values should be measured by setting a seed point or by designating a sample point of the boundary, thereby not only causing inconvenience in which an operator must be involved in the measurement, but also raising a problem in that the measured result may vary with each operator.